There have been provided various disc grinders, and FIGS. 1 and 2 show an example of conventional disc grinders.
A disc grinder 101 shown in FIGS. 1 and 2 includes a motor housing 102, a gear cover 103 attached to the front section of the motor housing 102 by screws 115a, 115b, and the like, a spindle case 104 attached to the gear cover 103, and a spindle 107 rotatably supported to the spindle case 104. The motor housing 102 accommodates a motor (not shown) therein, and the gear cover 103 accommodates a power transmission mechanism (not shown) for transmitting rotation of the motor to the spindle 107.
The disc grinder 101 also includes a wheel guard 105 for preventing grinding dust and other dirt from scattering toward an operator during grinding operations. The wheel guard 105 is mounted on the spindle case 104 coaxially with the spindle 107 so as to cover over about a half of a tool bit (not shown) on the operator side as shown in FIG. 1. The wheel guard 105 is provided with a fastening unit including a fastening ring 106, a screw 108, and a nut 109. The fastening ring 106 is attached to the wheel guard 105 and formed with a pair of bending parts 106a and 106b at ends thereof. The screw 108 is inserted through screw holes formed in the bending parts 106a and 106ba and engages with the nut 109. The fastening unit selectively fixes and unfixes the wheel guard 105 to and from the spindle case 104. The operator can determine a desired angle position of the wheel guard 105 by taking a working posture and the like into consideration and rotate the wheel guard 105 about a rotary axis of the spindle 107 in its circumferential direction to the desired angle position as shown in FIG. 2, after unscrewing the screw 108 to loosen the fastening ring 106.
FIG. 3 shows another conventional disc grinder 101A having the wheel guard 105 mounted on a spindle case 204, which is attached to a gear cover 203.
FIG. 4 shows still another conventional disc grinder 101B disclosed in Japanese Patent Application-Publication No. 2009-125841. The disc grinder 101B includes the wheel guard 105 mounted on a spindle case 304, which is attached to a gear cover 303. The wheel guard 105 is selectively fixed to and unfixed from the spindle case 304 by a fastening unit having a fastening ring divided into a pair of ring members 306A and 306B in a circumferential direction of the wheel guard 105, a screw 308 and a nut 309 that connect between edges of the ring members 306A and 306B on one side, and a fingertip fastening mechanism that selectively connects and separates the other edge 306a of the ring member 306A to and from the other edge of the ring member 306B on the other side when a lever 369 is operated. When the lever 369 is moved in a radial direction of the wheel guard 105, then the fastening ring is loosened to make the wheel guard 105 rotatable with respect to the spindle case 304.